Method and apparatus for monitoring connectivity in a long term evolution network

ABSTRACT

A method and apparatus for monitoring connectivity in a network at a bearer path layer are disclosed. For example, the method receives a request to monitor a user endpoint, identifies an internet protocol address of the user endpoint, an internet protocol address of each transport network element between the user endpoint and a bearer trace server, a bearer path identification of each bearer used by the user endpoint, a quality of service associated with each bearer used by the user endpoint, and a tunnel identification of each bearer used by the user endpoint; and performs a fault isolation and performance monitoring at a bearer path layer, wherein the fault isolation identifies a particular segment where a fault is detected at the bearer path layer.

The present disclosure relates generally to communication network and,more particularly, to a method and apparatus for monitoring aconnectivity in a wireless network, e.g., a Long Term Evolution (LTE)network.

BACKGROUND

When a user endpoint (UE) accesses a packet data network the user'sendpoint may have one or more connections to the packet data network(PDN) and each of the one or more connections may have one or morebearers. The data traffic to and from the user's endpoint is carried byone or more bearers. For each of the bearers used by a UE, a separateGeneral packet radio service (GPRS) Tunneling Protocol for User datatunneling (GTP-U) tunnel identification (TEID) data (broadly, tunnelidentification) is used. Each bearer may provide a specific quality ofservice (QoS) and an associated quality of class identifier (QCI).However, today connectivity between the user's endpoint and the packetdata network is monitored at an aggregate level for all users usinginternet protocol (IP) transport layer information for one or moresegments of the path. The monitoring of data at the Internet protocolpath layer provides no bearer level performance information about aspecific user endpoint's connections to the packet data network atvarious GTP segments of that path.

SUMMARY

In one embodiment, the present disclosure provides a method and anapparatus for monitoring a connectivity in a network at a bearer pathlayer. For example, the method receives a request to monitor a userendpoint, identifies an Internet protocol address of the user endpoint,an internet protocol address of each transport network element betweenthe user endpoint and a bearer trace server, a bearer pathidentification of each bearer used by the user endpoint, a quality ofservice associated with each bearer used by the user endpoint, and atunnel identification of each bearer used by the user endpoint; andperforms a fault isolation at a bearer path layer, wherein the faultisolation identifies a particular segment where a fault is detected atthe bearer path layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The teaching of the present disclosure can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates an exemplary LTE network related to the presentdisclosure;

FIG. 2 illustrates an exemplary continuity monitoring at a bearer pathlayer;

FIG.3 illustrates an exemplary protocol stack for an LBTrequest/response loop initiated by an LBT server to an eNodeB;

FIG. 4 illustrates a flowchart of a method for monitoring connectivityin a network at a bearer path layer and at a transport layer; and

FIG. 5 illustrates a high level block diagram of a general purposecomputer suitable for use in performing the functions described herein;

DETAILED DESCRIPTION

The present disclosure broadly describes a method and an apparatus formonitoring connectivity and bearer layer performance in a wirelessnetwork, e.g., a Long Term Evolution (LTE) network. Although theteachings of the present disclosure are discussed below in the contextof LTE networks, the teaching is not so limited. Namely, the teachingsof the present disclosure can be applied for other types of wireless orcellular networks in accordance with other standards, e.g., 2G networks,3G networks, etc.

3GPP is a global effort to define a wireless communication systemspecification. In 3GPP release 8, LTE is a set of enhancements to theUniversal Mobile Telecommunications System (UMTS) which focuses onadopting 4th Generation (4G) mobile communications technology, includingan all Internet Protocol (IP) end-to-end network architecture. Broadlydefined, an eNodeB is a radio base transceiver station (RBS) as per the3GPP standards (or simply referred to as a base station). An eNodeBprovides the LTE air interface and performs radio resource managementfor wireless access.

In a 3GPP Long Term Evolution (LTE) network, connectivity may bedisrupted at various layers of a network. For example, the Internetprotocol layer may operate normally while a user endpoint isexperiencing poor quality of service.

To address this criticality, the present method and apparatus providesfor real time monitoring of user connectivity at the bearer path layer.The method provides performance measurements for each of the user'sbearers. For example, the method measures round trip times such as butnot limited to (RTTs), available bit rates, packet loss ratios, andpacket delay variations (a.k.a. Jitter): between an eNodeB that a beareris using and a server in the packet network; for each segment along atraversed path between the eNodeB and the server in the packet network,etc. If a particular connectivity is found to be faulty, the method canthen isolate the fault to a specific segment of the network.

FIG. 1 illustrates an exemplary LTE network 100 related to the presentdisclosure. In one illustrative embodiment, the LTE network 100comprises an access network 102 (e.g., an evolved Universal TerrestrialRadio Access Network (eUTRAN)), a backhaul network 109, a core network103 (e.g., an Evolved Packet Core (EPC) network), and a control system104, e.g., supported and operated by a wireless service provider. Itshould be noted that control system 104 can be deployed in any of thenetwork illustrated in FIG. 1. Furthermore, although various networksare shown as separate networks in FIG. 1, it is possible that functionsperformed by these networks can be combined into fewer networks orexpanded into a greater number of networks depending on the deploymentrequirements.

In one illustrative example, the eUTRAN, e.g., eUTRAN 102, may compriseone or more eNodeBs, e.g., 111. In operation, user equipment or userendpoint (UE) 101 may access wireless services via an eNodeB, e.g.,eNodeB 111 in the eUTRAN 102. UE 101 can be a smart phone, a cellularphone, a computing tablet, a computer or laptop, or any endpointcommunication devices equipped with wireless capabilities. An eNodeB,such as eNodeB 111, provides wireless interfaces to one or more UEdevices. All eNodeBs in the eUTRAN 102 are connected to the EPC network103 via one or more integrated access devices 105 (e.g., a SmartIntegrated Access Device (SIAD)) located in a backhaul network 109.Broadly, an integrated access device is capable of integrating bothvoice and data services within a single device. In one embodiment,eNodeB 111 supports wireless services covered by one or more cell siteslocated in eUTRAN 102. It should be noted that any number of eNodeBs canbe deployed.

In one embodiment, eUTRAN 102 is connected to the EPC network 103 viathe backhaul network 109. For example, SIAD 105 in the backhaul network109 is connected to the EPC network 103 via a Multi-service Node (MSN)106. An EPC network provides various functions that support wirelessservices in the LTE environment. In one embodiment, an EPC network is anInternet Protocol (IP) packet core network that supports both real-timeand non-real-time service delivery across a LTE network, e.g., asspecified by the 3GPP standards.

In one embodiment, the SIAD is a device that provides wireless trafficaggregation and backhaul from a cell site to an EPC network. An MSNprovides layer 2 and layer 3 networking functions for wireless servicebetween one or more SIADs and the EPC network. The eUTRAN 102 is the airinterface of the 3GPP's Long Term Evolution (LTE) specifications formobile networks. Namely, the eUTRAN comprises a radio access networkstandard that will replace previous generations of air interfacestandards.

In one embodiment, the SIAD 105 and the MSN 106 communicate over abackhaul network 109. The backhaul network may also be referred to as ametro Ethernet transport network.

In EPC network 103, network devices such as Mobility Management Entity(MME) 107 and Serving Gateway (SGW) 108 support various functions aspart of the LTE network 100. For example, MME 107 is the control nodefor the LTE access-network. In one embodiment, it is responsible for UE(User Equipment) tracking and paging (e.g., such as retransmissions),bearer activation and deactivation process, selection of the SGW, andauthentication of a user. In one embodiment, SGW 108 routes and forwardsuser data packets, while also acting as the mobility anchor for the userplane during inter-eNodeB handovers.

In addition, EPC (common backbone) network 103 may comprise a HomeSubscriber Server (HSS) 191 that contains subscription-relatedinformation (e.g., subscriber profiles), performs authentication andauthorization of a wireless service user, and provides information aboutthe subscriber's location. The EPC network 103 may also comprise aPolicy and Charging Enforcement Point (PCEF) 192 that supports accessesto subscriber databases and specialized functions of a charging system.The EPC network 103 may also comprise a Public Data Network Gateway (PDNGW) 193 which serves as a gateway that provides access between the EPCnetwork 103 and various data networks, e.g., other IP networks, trustedor non-trusted networks 194-196 and the like. The PDN GW may also bereferred to as a PGW. PGW also serves as the anchor for mobility betweenLTE and other wireless technologies, such as 2G and 3G wirelessnetworks. It should be noted that the above illustrated LTE network 100is only illustrative and the number of network components or elementsare not specifically limited as shown. Any number of network componentsor elements can be deployed.

In one embodiment, the control system 104 comprises a collection ofmodules that provides monitoring connectivity in the LTE network. Forexample, the control system 104 may comprise a network monitoring module131, a controller 132, a discovery module (discovery subsystem) 133, aconfiguration management and subscriber data application module 134. Infact, in one embodiment, the control system 104 may also include the LBTserver 197 as discussed below. The functions performed by these moduleswill be described below. It should be noted that these various modulesmay perform other functions. Only the functions relates to the presentdisclosure are herein described. Furthermore, although these modules areillustrated as separate modules, the functions performed by thesemodules can be implemented in one or more hardware systems, e.g., in asingle application server, in a plurality of application servers, andthe like.

In one embodiment, the eUTRAN network 102, the backhaul network 109 andthe EPC network 103 include various data bearer paths and signalingbearer paths. The various bearer paths may be referred to by specificlabels. For example, the data bearer path on line 152 may be referred toas an S1-U bearer path and the data bearer path on line 153 may bereferred to as an S5 or an S8 bearer path. In another example, thesignaling bearer path between the eUTRAN and the MME 107 may be referredto as an S1-MME bearer path. Note that the S1, S5, S8 and SGi interfacesare standard interfaces defined by the 3GPP standard. It should be notedthat the present disclosure is not limited to these specific interfaces.

Shown illustratively in FIG. 1, the S1 interface flow 152 is used toprovide communication between an eNodeB, such as eNodeB 111, and adevice in the EPC network 103, such as MME 107 and/or SGW 108. The SGiinterface flow 154 is used to provide communication between the PGW 193(also referred to as PDN GW 193) and the PCEF 192. The S5/S8 interfaceflow 153 is used to provide communication between the SGW 108 and PGW193.

In one embodiment, the network monitoring module 131 monitors networkelements in EPC 103 and reports troubles to a controller 132. In oneembodiment, the configuration management and subscriber data applicationmodule 134 may provide additional information as needed, e.g., such asnode identity based on the network configuration data. The controller132 processes commands received from a user 136, e.g., commands tomonitor one or more UEs. For example, UE 101 may be experiencing adegradation of service quality. The monitoring of data at the internetprotocol and path layers provides no information about a specific userendpoint's connections and experience to the packet data network. Forexample, UE 101 may be experiencing service degradation and the faultmay not be detectable at the internet protocol and path layers.

In one embodiment, the present disclosure provides bearer path layerconnectivity and performance monitoring such that fault isolation may beperformed at the bearer path layer. Fault isolation at the bearer pathlayer enables identification of a particular network segment wherein thefault is located, such as an indication that a silent packet forwardingissue exists. For example, if UE 101 is experiencing servicedegradation, a user 136 (e.g., a work center personnel) may issue acommand to the controller 132 to monitor bearer paths used for packetsto and from the UE 101. In turn, the controller 132 is able to invokefault isolation. In order to perform the fault isolation for aparticular UE, the current method sends bearer path layer trace packets(broadly bearer trace packets) from a server on the same bearer pathstraversed by the subscriber's packets of the particular UE. Thus, thebearer trace packets and the subscriber's packets experience a samelevel of service (e.g., a same level of degradation) while utilizingeach bearer path. The server used to send the bearer path layer tracepackets and receive the corresponding responses is referred to as a longterm evolution bearer trace (LBT) server (broadly referred to as abearer trace server). For example, FIG. 1 illustrates an LBT server 197that may be used to send the bearer path layer trace packets.

In order to transmit the trace packets on the same bearer pathstraversed by the subscriber's packets, the controller first needs toknow the particular bearer paths used for the subscriber's packets. Inone embodiment, the controller 132 engages the discovery subsystem 133in order to identify the internet protocol addresses of the UE and thetransport network elements between the UE and the LBT server. In oneembodiment of a discovery subsystem, 133, first determines the internetprotocol address of the MME being used by the particular UE from thehome subscriber server. For example, for the UE 101 illustrated in FIG.1, the discovery subsystem 133 may access the HSS 191 to determine theIP address of the MME 107. The discovery subsystem 133 then interactswith the MME 107 to determine: the IP addresses of the UE, eNodeB, SGW,PGW, PCEF, etc. between the LBT server and the UE, bearer identificationof each of the bearers used by the UE, a quality of service (QoS)associated with each bearer, and General packet radio service TunnelingProtocol for User data tunneling (GTP-U) tunnel identification (TEID)data (broadly, tunnel identification) of each of the bearers used by theUE.

Note that a UE may have multiple connections to the EPC networkinvolving any number of PGWs simultaneously. The UE would then have adifferent IP address for each of the connections. In addition, eachconnection may involve multiple PGWs and/or SGWs. The discoverysubsystem described above may then be used to discover each IP addressof the UE, and the respective IP addresses of the eNodeB, SGW, PGW,PCEF, etc. between the LBT server and the UE.

FIG. 2 illustrates an exemplary continuity monitoring 200 at a bearerpath layer. The continuity monitoring 200 is used to isolate faults to asegment between the eNodeB 111 and the LBT server 197, and to performperformance measurements. The fault isolation is accomplished by usingone or more LBT request/response loops (broadly referred to asrequest/response loops) combined with one or more enhanced trace-routeloops. The enhanced trace-route loop is also referred to as aping/trace-route loop. Other request/response protocols, Two-Way ActiveMeasurement Protocol (TWAMP) being one example of many, may be used inaddition to or instead of ping or traceroute.

Note that the end-to-end service comprises: S1 bearer paths between aneNodeB and an SGW; S5/S8 bearer paths between the SGW and a PGW; and oneor more SGi bearer paths (between the PGW and a PCEF and between thePCEF and a server). Each S1 and S5/S8 bearer path is carried by GTPtunnels in the uplink and downlink directions. The LBT request/responseloops exercise these GTP tunnels in both the uplink and downlinkdirections. The ping/trace-route loops are used for exercising loopsthat do not involve GTP tunnels.

The LBT request/response loops are used for isolating a fault to asegment, wherein the fault is between the eNodeB and the SGW. An LBTrequest/response loop and an enhanced trace-route loop are used forisolating a fault to a segment, wherein the fault is between the SGW andthe PGW. The enhanced trace-route loops are used for isolating a faultto a segment, wherein the fault is either between the PGW and the PCEFor between the PCEF and the LBT server.

The destination address for an LBT request/response loop is an IPaddress of the network transport device intended to reflect back themessage in the form of a response. For example, in FIG. 2, the LBTrequests for exercising loops 201 and 202 originate in the LBT server197. The destination of the LBT request for exercising loop 201 is theeNodeB 111. The destination of the LBT request for exercising loop 202is the SGW 108. The LBT requests are then reflected in accordance withthe respective destination. The eNodeB 111 provides a response for loop201 and SGW 108 provides a response for loop 202.

The destination address for an enhanced trace-route loop is the IPaddress of the UE, so the path taken by the trace route packet is thesame as that of the user packets. Note that an ordinary ping to the IPaddress of the UE would not be reflected back by the PCEF or PGW.However, a ping to the IP address of the PGW and PCEF would follow thepath of the user's packets. Thus, the enhancement (i.e., a pingaddressed to the PGW or PCEF along with the trace functionality) enablesthe enhanced trace-route packets to take the same path taken by the userpackets. Thus, the destinations of the enhanced trace-route loops forexercising loops 203 and 204 are that of the UE 101. For example, inFIG. 2, the enhanced trace-route loops (ping/trace-route loops) forexercising loops 203 and 204 originate in the LBT server 197. However,the ping for loop 203 has a destination, wherein the destination is theIP address of the PGW 193. Similarly, the ping for loop 203 has adestination, wherein the destination is the IP address of the PCEF 192.

A single failure on any segment, by using two enhanced trace-route loopsand two LBT request/response loops, may then be detected and isolated toa particular segment between the LBT server and the eNodeB. For example,in FIG. 2, if the LBT request/response for loop 201 is not successfuland the LBT request/response for loop 202 is successful, a fault isdetected between the eNodeB 111 and the SGW 108. In another example, ifthe LBT request/response for loop 202 is not successful and theping/trace-route loop 203 is successful, a fault is detected between theSGW 108 and the PGW 193. In another example, if the ping/trace-routeloop 203 is not successful and the ping/trace-route loop 204 issuccessful, a fault is detected between the PGW 193 and the PCEF 192. Inanother example, if the ping/trace-route loop 204 is not successful, afault is detected between the PCEF 192 and the LBT server 197.

Similarly, a round-trip-time may be measured for each segment. Note thatthe LBT request/response loops and the enhanced trace-route loops carrytimestamps and sequence numbers. The timestamps and sequence numbers maythen be used to measure round-trip-times and to determine a direction inwhich a fault has occurred, etc.

The method then provides a report to the user. For example, the methodmay report to the user that a fault is detected and the fault isisolated to a particular segment. The method may also provideperformance data (e.g., round-trip-times).

As described above, the packets for the LBT request/response loopsfollow the same paths as the packets intended for the subscriber's UE.The protocol stacks for transport of the packets for the LBTrequest/response loops are the same as for subscriber packets. In oneembodiment, the present method enables a particular loop to be exercisedwithout imposing a packet inspection deeper than the GTP-U header byintermediate transport network devices.

In particular, the LBT server that originates the LBT request/responseloop sets a UDP destination port number of the request to indicate thedestination to which the request is intended. For example, the UDP portnumber in the LBT request originated by the LBT server may be that ofthe eNodeB or the SGW. The source port number in the LBT requestindicates the port number of the LBT server used to originate the LBTrequest. It should be noted that using UDP source and/or destinationport numbers is one illustrative implementation to indicate thedestination to which the request is intended. However, other fields inthe IP header, such as source and destination IP addresses, protocol-id,and others, may also be used for this purpose.

When the LBT request arrives at a PGW, the PGW inspects packets receivedfrom an IP address of the LBT server. The PGW determines the UDP portnumber indicating the destination device to which the LBT request isintended. The PGW then encapsulates the packets and sets the value ofthe GTP-U header message-type to indicate that the destination is eitherthe eNodeB or the SGW. When the GTP-U encapsulated packet arrives at theSGW, the message-type is inspected to determine the appropriate actionto be taken by the SGW. Based on the message-type, the SGW eitherprocesses and reflects the LBT request or forwards the LBT requesttowards the eNodeB. For example, if the message-type indicates that therequest is intended for the SGW, the SGW sends back a response towardsthe LBT server. If the message-type indicates that the request isintended for the eNodeB, the SGW forwards the request towards theeNodeB. Similarly, when the packet arrives at the eNodeB, the eNodeBinspects the packet to determine the appropriate action. In this case,the eNodeB processes the request and provides a response—withoutforwarding the request to the UE.

FIG. 3 illustrates an exemplary protocol stack 300 for an LBTrequest/response loop initiated by an LBT server to an eNodeB. Notethat, for this particular example, the PCEF function is included in thePGW.

First, in the downlink direction (from LBT server towards UE), the LBTserver 197 sets the UDP port number (UDP Dprt) to indicate that therequest is to the eNodeB 111 and the request is initiated by the LBTserver 197.

For example, the protocol stack may be as illustrated in 301:

-   -   S=IPA(LBT server)    -   D=IPA(UE)    -   UDP        -   Sprt (LBT protocol)        -   Dprt (eNB LBT)

When the request reaches the PGW 193, the PGW inspects the receivedpackets with the source IP address of the LBT server and UDP Dprtindicating server initiated LBT request for an eNodeB, the PGWencapsulates the packets in a GTP with a msg-type set to indicate an LBTserver initiated request for the eNodeB. For example, the protocol stackfrom the PGW may then be as illustrated in 302.

-   -   Outer Packet (GTP-U)        -   S=IPA(S5 PGW)        -   D=IPA(S5 SGW)    -   UDP        -   Sprt PGW assigned        -   Dprt 2152    -   GTP        -   msg-typ (eNB LBT)        -   TEID S5 DL    -   Inner packet        -   S=IPA(LBT server)        -   D=IPA(UE)    -   UDP        -   Sprt (LBT protocol)        -   Dprt (eNB LBT)

When the request reaches the SGW 108, the SGW 108 inspects the messagetype and determines that the request is intended for the eNodeB andforwards the request to the eNodeB. The protocol stack from the SGW maythen be as illustrated in 303.

-   -   Outer Packet (GTP-U)        -   S=IPA(S1 SGW)        -   D=IPA(S1 eNB)    -   UDP        -   Sprt SGW assigned        -   Dprt 2152    -   GTP        -   msg-typ (eNB LBT)        -   TEID S1 DL    -   Inner packet        -   S=IPA(LBT server)        -   D=IPA(UE)    -   UDP        -   Sprt (LBT protocol)        -   Dprt (eNB LBT)

When the request reaches the eNodeB, the eNodeB inspects the messagetype. The eNodeB then processes the request and generates a response tothe request (i.e., reflects the request). The response is then to beforwarded in the uplink direction (in the direction from UE towards theLBT server). The protocol stack from the eNodeB may then be asillustrated in 304.

-   -   Outer Packet (GTP-U)        -   S=IPA(S1 eNB)        -   D=IPA(S1 SGW)    -   UDP        -   Sprt eNB assigned        -   Dprt 2152    -   GTP        -   msg-typ 255        -   TEID S1 UL    -   Inner packet        -   S=IPA(UE)        -   D=IPA(LBT server)    -   UDP        -   Sprt (eNB LBT)        -   Dprt (LBT protocol)

When the response packets from the eNodeB are received by the SGW 108,the SGW inspects the packets and forwards the response towards the PGW193. The protocol stack from the SGW 108 in the uplink direction maythen be as illustrated in 305.

-   -   Outer Packet (GTP-U)        -   S=IPA(S5 SGW)        -   D=IPA(S5 PGW)    -   UDP        -   Sprt SGW assigned        -   Dprt 2152    -   GTP        -   msg-typ 255        -   TEID S5 UL    -   Inner packet        -   S=IPA(UE)        -   D=IPA(LBT server)    -   UDP        -   Sprt (eNB LBT)        -   Dprt (LBT protocol)

The PGW 193 receives the response packets, removes the encapsulation andforwards the response towards the LBT server 197. The protocol stackfrom the PGW 193 in the uplink direction may then be as illustrated in306.

-   -   S=IPA(UE)        -   D=IPA(LBT server)        -   UDP            -   Sprt (eNB LBT)            -   Dprt (LBT protocol)

When the LBT server 197 receives the response, the LBT determineswhether the LBT request/response was successful. Similarly, protocolstacks for LBT request/response loops may be addressed to an SGW. Theresponses received by the LBT server are similar with the exception ofthe source port number associated with the response. The LBT server thendistinguishes responses reflected by an eNodeB from responses reflectedby an SGW from the source port numbers (Sprt) of the received packets.

When all the desired loops are exercised, the method then isolatesfaults to a segment level and provides a response to the user. Forexample, the response to the user may identify a particular segmentwherein the fault occurred and any relevant performance data (e.g.,round trip times).

It should be noted that the above examples are only illustrative. Inother words, other protocol fields, such as others in the GTP header,may be used instead of or in addition to GTP message-type to carry theindication of the desired destination of the request message from theLBT server. This information may also be used to provide moreinformation about the contents and purpose of the request and responsemessages. For example, it could provide information about the datainside the payload of the request/response messages and how those fieldsare to be processed in the elements that the messages pas through.

FIG. 4 illustrates a flowchart of a method 400 for monitoringconnectivity in a network at a bearer path layer. For example, themethod 400 may be implemented in a controller. Method 400 starts in step403 and proceeds to step 405.

In step 405, method 400 receives a request from a user to monitor a UE.For example, a UE may be experiencing a degradation of service. A user(e.g., work center personnel) may then send a request to a controllerfor monitoring of the UE at a bearer path layer such that faultisolation may be performed at the bearer path layer.

In step 410, method 400 identifies: all Internet protocol addresses ofthe UE, Internet protocol addresses of each transport network elementbetween the UE and an LBT server, bearer path identifications of eachbearer used by the UE, and quality of service (QoS) and GTP-U tunnelidentification (TEID) data of each of the bearers used by the UE. In oneembodiment, the identifying of all internet protocol addresses of theUE, Internet protocol addresses of each transport network elementbetween the UE and an LBT server, bearer path identifications of eachbearer used by the UE, and quality of service (QoS) and GTP-U tunnelidentification data of each of the bearers used by the UE is performedvia a discovery subsystem.

In one embodiment, the discovery subsystem may receive from thecontroller a command to perform the discovery for a particular UE. Thediscovery subsystem may then first determine the Internet protocoladdress of the MME being used by the particular UE from the homesubscriber server. For example, for the UE 101 illustrated in FIG. 1,the discovery subsystem 133 may access the HSS 191 to determine the IPaddress of the MME 107. The discovery subsystem 133 may then read theMME 107 to determine: the IP addresses of the UE, eNodeB, SGW, PGW,PCEF, etc. between an LBT server and the UE; bearer identifications ofeach of the bearers used by the UE; and quality of service (QoS) andGTP-U tunnel identification (TEID) data of each of the bearers used bythe UE. The discovery subsystem may then provide the IP addresses of theUE, eNodeB, SGW, PGW, PCEF, etc. between an LBT server and the UE;bearer identifications of each of the bearers used by the UE; andquality of service (QoS) and GTP-U tunnel identification data of each ofthe bearers used by the UE to the controller.

In step 420, method 400 performs fault isolation at the bearer pathlayer, wherein the fault isolation identifies a particular segment wherea fault is detected at the bearer path layer. The performing the faultisolation is accomplished in accordance with the internet protocoladdresses of the UE, internet protocol addresses of each transportnetwork element between the UE and an LBT server, bearer pathidentifications of each bearer used by the UE, and quality of service(QoS) and GTP-U tunnel identification (TEID) data of each of the bearersused by the UE. In one embodiment, the segment is located between aneNodeB serving the UE and the LBT server. Note that there are aplurality of segments between the eNodeB serving the UE and the LBTserver. The goal is to isolate the fault to a particular segment of theplurality of segments. The fault isolation is accomplished by invokingone or more LBT request/response loops combined with one or moreenhanced trace-route loops. In one embodiment, the loops are originatedby an LBT server that receives a command from the controller to isolatea fault to a particular segment at the bearer path layer.

For example, the method may instruct the LBT server to send: a first LBTrequest to the eNodeB, a second LBT request to an SGW, a first enhancedtrace-route request to a PGW, and a second enhanced trace-route requestto a PCEF. For example, for the UE shown in FIG. 2, the controller mayinstruct the LBT server 197 to send the requests as follows. The firstLBT request is associated with loop 201, the second LBT request isassociated with loop 202, the first enhanced trace-route request isassociated with loop 203 and the second enhanded trace-route request isassociated with loop 204. A response is then received for each of theLBT requests and for each of the enhanced trace-route requests. Thefault isolation is then performed in accordance with the responses. Forexample, if the LBT request/response for loop 201 is not successful andthe LBT request/response for loop 202 is successful, a fault is detectedbetween the eNodeB 111 and the SGW 108. In another example, if the LBTrequest/response for loop 202 is not successful and the ping/trace-routeloop 203 is successful, a fault is detected between the SGW 108 and thePGW 193. In another example, if the ping/trace-route loop 203 is notsuccessful and the ping/trace-route loop 204 is successful, a fault isdetected between the PGW 193 and the PCEF 192. In another example, ifthe ping/trace-route loop 204 is not successful, a fault is detectedbetween the PCEF 192 and the LBT server 197. In another example, a faultis detected where the fault is silent and no other messaging or alarmingexists to identify the fault, e.g., silent packet forwarding loss.

In optional step 430, the method performs performance measurements,e.g., measure round-trip times for each segment between the eNodeBserving the UE and the LBT server. For example, time stamps and sequencenumbers carried in LBT request/response loops and the enhancedtrace-route loops may be used for determining round-trip times. Itshould be noted that various performance measurements can be made, e.g.,measuring one-way delay of a packet associated with a particularsegment, verifying a payload integrity of packets to detect any packetcorruption along the path, performing a quality of service verification,performing an available bandwidth calculation or verification as definedpursuant to a service level agreement (SLA), and so on.

In step 440, method 400 provides a report to the user. The report mayinclude the result of the fault isolation, round-trip times per segment,etc. For example, a report that indicates a fault at the bearer pathlayer on a particular segment between an eNodeB serving the UE and theLBT server may be sent from the controller to the user.

In one embodiment, when a fault is detected, an alarm is sent tonorthbound systems using Simple Network Management Protocol (SNMP)traps. For example, a table is built which identifies the failure typeor category and the SNMP trap for each failure type. The table existsoutside of LBT but is an expected input to LBT when LBT is running. Thisallows for changes in alarm types and traps as needed by a particularorganization.

In step 450, method 400 determines if there are more requests that arereceived for monitoring a UE. If there is another request that isreceived, the method proceeds to step 405. Otherwise, the methodproceeds to step 495 to end the current process.

In one embodiment, the fault isolation and performance monitoring at thebearer path layer may include isolation of faults that occur between theUE and the eNodeB. For example, an additional LBT request/response loopmay be sent with a destination address of the request being that of theUE. If the fault isolation method includes isolation faults that occurbetween the UE and the eNodeB, the eNodeB, after inspecting a packet todetermine the appropriate action, forwards to the UE the requestintended for the UE.

In one embodiment, the eNodeB may comprise a software based UE modulethat resides within the eNodeB with or without engaging the Uu/airinterface procedures. The software based UE module has no Radio AccessBearers (RABs) or Uu interface but is able to initiate PDN connectionrequests, bearer path setup requests, etc. in a similar manner as thereal UE. For example, the service provider may not have permission fromthe subscriber to send the LBT request packets to the subscriber's UE.The current method is then able to include fault isolation for faultsbetween a SW UE at the eNodeB and the rest of the network path—withoutthe LBT requests having to reach a subscriber UE. For example, thesoftware based UE module may receive the LBT request and provide acorresponding response.

In one embodiment, the method may utilize a UE dedicated for monitoring(e.g., a monitoring UE) such that the fault isolation and performancemonitoring may include isolation of faults that occur between a UE andthe eNodeB. For example, the service provider may not have permissionfrom the subscriber to send the LBT request packets to the subscriber'sUE. However, the service provider has permission to send packet to themonitoring UE. The monitoring UE may then receive the LBT request andprovide a response.

In one embodiment, there may be remote devices off the internetsomewhere that are “LBT Aware” (i.e., contain LBT stacks), such that youcould set up bearer traces to just about any location where an LBT awaredevice is present. This would help enterprises interested in bearerperformance measurement over their networks. LBT Aware devices wouldenable enterprises to check the bearer layer (GTP) against servicelevels, critical for mobility networks.

In the description above, the bearer paths are assumed to be establishedwhen the fault isolation is invoked. However, in the idle state, the S1bearer path no longer exists. Thus, waking up the UE may be needed priorto measuring performance and invoking the fault isolation procedure. TheLBT server may be configured to send packets towards the UE in order toinitiate a return of the UE to a connected state, wherein the S1 bearerpath is reestablished. The method may then invoke the fault isolationand performance measurement after the S1 bearer path is reestablished.

In one embodiment, the LBT request/response loops and the enhancedtrace-route loops may be originated by an eNodeB and sent in thedirection of the LBT server. For example, the requests may be sent bythe eNodeB towards the LBT server and the responses may be sent back tothe eNodeB. Accordingly, the present method provides a protocol stackfor the requests originated by the eNodeB and responses provided by thevarious network elements between the eNodeB and the LBT server. As such,the protocol stack described in FIG. 3 is intended to be exemplary andnot limiting the implementation of the present disclosure.

In one embodiment, the controller may instruct the LBT server to sendthe LBT request/response loops and the enhanced trace-route loopsdescribed above. In another embodiment, the LBT server may initiate thefault isolation and performance monitoring—without the need forreceiving by the LBT server an instruction from a controller.

In one embodiment, the fault isolation and performance monitoring at thebearer path layer of the present disclosure also determines when abearer management activity (e.g., handovers) is occurring. Thus,handover activity is not reported as a fault.

It should be noted that although not explicitly specified, one or moresteps of the method 400 described herein may include a storing,displaying and/or outputting step as required for a particularapplication. In other words, any data, records, fields, and/orintermediate results discussed in the method can be stored, displayed,and/or outputted to another device as required for a particularapplication. Furthermore, steps or blocks in FIG. 4 that recite adetermining operation, or involve a decision, do not necessarily requirethat both branches of the determining operation be practiced. In otherwords, one of the branches of the determining operation can be deemed asan optional step.

FIG. 5 depicts a high level block diagram of a general purpose computersuitable for use in performing the functions described herein. Asdepicted in FIG. 5, the system 500 comprises a processor element 502(e.g., a CPU), a memory 504, e.g., random access memory (RAM) and/orread only memory (ROM), a module 505 for monitoring connectivity in anetwork at a bearer path layer, and various input/output devices 506(e.g., storage devices, including but not limited to, a tape drive, afloppy drive, a hard disk drive or a compact disk drive, a receiver, atransmitter, a speaker, a display, a speech synthesizer, an output port,and a user input device (such as a keyboard, a keypad, a mouse, and thelike)).

It should be noted that the present disclosure can be implemented insoftware and/or in a combination of software and hardware, e.g., usingapplication specific integrated circuits (ASIC), a general purposecomputer or any other hardware equivalents, e.g., computer readableinstructions pertaining to the method(s) discussed above can be used toconfigure a hardware processor to perform the steps of the abovedisclosed method. In one embodiment, the present module or process 505for monitoring connectivity in a network at a bearer path layer can beloaded into memory 504 and executed by processor 502 to implement thefunctions as discussed above. As such, the present process 505 formonitoring connectivity in a network at a bearer path layer (includingassociated data structures) of the present disclosure can be stored on anon-transitory (e.g., tangible and physical) computer readable storagemedium, e.g., RAM memory, magnetic or optical drive or diskette and thelike.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

1. A method for monitoring a connectivity in a network, comprising:receiving a request to monitor a user endpoint; identifying an internetprotocol address of the user endpoint, an internet protocol address ofeach transport network element between the user endpoint and a bearertrace server, a bearer path identification of each bearer used by theuser endpoint, a quality of service associated with each bearer used bythe user endpoint, and a tunnel identification of each bearer used bythe user endpoint; and performing a fault isolation at a bearer pathlayer, wherein the fault isolation identifies a particular segment wherea fault is detected at the bearer path layer.
 2. The method of claim 1,wherein the performing the fault isolation comprises: invoking arequest/response loop.
 3. The method of claim 2, wherein therequest/response loop is originated by the bearer trace server.
 4. Themethod of claim 1, wherein the performing the fault isolation comprises:invoking a ping/trace-route loop.
 5. The method of claim 4, wherein theping/trace-route loop is originated by the bearer trace server.
 6. Themethod of claim 1, further comprising: performing a performancemeasurement.
 7. The method of claim 6, wherein the performing theperformance measurement comprises at least one of: measuring around-trip time of a packet associated with a particular segment;measuring a one-way delay of a packet associated with a particularsegment; verifying a payload integrity of packets to detect any packetcorruption; verifying a quality of service; and verifying an availablebandwidth.
 8. The method of claim 1, further comprising: providing areport to a user of the fault.
 9. The method of claim 1, furthercomprising: determining when a bearer management activity is occurringfor the user endpoint.
 10. The method of claim 9, wherein bearermanagement activity is a handover activity.
 11. The method of claim 1,further comprising: waking up the user endpoint prior to the performingthe fault isolation.
 12. The method of claim 1, wherein the userendpoint is a monitoring user endpoint.
 13. The method of claim 1,wherein the user endpoint is a software module that resides within aneNodeB, wherein the eNodeB is serving as the user endpoint.
 14. Themethod of claim 1, wherein the performing the fault isolation furthercomprises: isolating of a fault that occurs between the user endpointand an eNodeB serving the user endpoint.
 15. The method of claim 1,wherein the internet protocol address of each transport network elementbetween the user endpoint and the bearer trace server comprises anInternet protocol address of an eNodeB serving the user endpoint. 16.The method of claim 1, wherein the internet protocol address of eachtransport network element between the user endpoint and the bearer traceserver comprises an internet protocol address of a serving gatewayserving the user endpoint.
 17. The method of claim 1, wherein theinternet protocol address of each transport network element between theuser endpoint and the bearer trace server comprises an internet protocoladdress of a public data network gateway serving the user endpoint. 18.The method of claim 1, wherein the internet protocol address of eachtransport network element between the user endpoint and the bearer traceserver comprises an Internet protocol address of a policy and chargingenforcement point serving the user endpoint.
 19. A non-transitorycomputer-readable medium having stored thereon a plurality ofinstructions, the plurality of instructions including instructionswhich, when executed by a processor, cause the processor to perform amethod for monitoring a connectivity in a network, comprising: receivinga request to monitor a user endpoint; identifying an internet protocoladdress of the user endpoint, an internet protocol address of eachtransport network element between the user endpoint and a bearer traceserver, a bearer path identification of each bearer used by the userendpoint, a quality of service associated with each bearer used by theuser endpoint, and a tunnel identification of each bearer used by theuser endpoint; and performing a fault isolation at a bearer path layer,wherein the fault isolation identifies a particular segment where afault is detected at the bearer path layer.
 20. An apparatus formonitoring a connectivity in a network, comprising: a processor; and acomputer-readable medium in communication with the processor, whereinthe computer-readable medium having stored thereon a plurality ofinstructions, the plurality of instructions including instructionswhich, when executed by the processor, cause the processor to perform amethod, comprising: receive a request to monitor a user endpoint;identify an internet protocol address of the user endpoint, an internetprotocol address of each transport network element between the userendpoint and a bearer trace server, a bearer path identification of eachbearer used by the user endpoint, a quality of service associated witheach bearer used by the user endpoint, and a tunnel identification ofeach bearer used by the user endpoint; and perform a fault isolation ata bearer path layer, wherein the fault isolation identifies a particularsegment where a fault is detected at the bearer path layer.